title: Geometry-independent inclusion of basal myocardium yields improved cardiac magnetic resonance agreement with echocardiography and necropsy quantified left-ventricular mass.
abstract: OBJECTIVE
  Left-ventricular mass (LVM) is widely used to guide clinical decision-making. Cardiac magnetic resonance (CMR) quantifies LVM by planimetry of contiguous short-axis images, an approach dependent on reader-selection of images to be contoured. Established methods have applied different binary cut-offs using circumferential extent of left-ventricular myocardium to define the basal left ventricle (LV), omitting images containing lesser fractions of left-ventricular myocardium. This study tested impact of basal slice variability on LVM quantification.
  
  
  METHODS
  CMR was performed in patients and laboratory animals. LVM was quantified with full inclusion of left-ventricular myocardium, and by established methods that use different cut-offs to define the left-ventricular basal-most slice: 50% circumferential myocardium at end diastole alone (ED50), 50% circumferential myocardium throughout both end diastole and end systole (EDS50).
  
  
  RESULTS
  One hundred and fifty patients and 10 lab animals were studied. Among patients, fully inclusive LVM (172.6±42.3g) was higher vs. ED50 (167.2±41.8g) and EDS50 (150.6±41.1g; both P<0.001). Methodological differences yielded discrepancies regarding proportion of patients meeting established criteria for left-ventricular hypertrophy and chamber dilation (P<0.05). Fully inclusive LVM yielded smaller differences with echocardiography (Δ=11.0±28.8g) than did ED50 (Δ=16.4±29.1g) and EDS50 (Δ=33.2±28.7g; both P<0.001). Among lab animals, ex-vivo left-ventricular weight (69.8±13.2g) was similar to LVM calculated using fully inclusive (70.1±13.5g, P=0.67) and ED50 (69.4±13.9g; P=0.70) methods, whereas EDS50 differed significantly (67.9±14.9g; P=0.04).
  
  
  CONCLUSIONS
  Established CMR methods that discordantly define the basal-most LV produce significant differences in calculated LVM. Fully inclusive quantification, rather than binary cut-offs that omit basal left-ventricular myocardium, yields smallest CMR discrepancy with echocardiography-measured LVM and non-significant differences with necropsy-measured left-ventricular weight.
authors.affiliation: aDepartment of Medicine (Cardiology) bDepartment of Radiology cDepartment of Biomedical Engineering, Weill Cornell Medical College dMemorial Sloan Kettering Cancer Center eIBM TJ Watson Research Center, Yorktown, New York fHeart South Cardiovascular Group, Alabaster, Alabama gUCLA Health System, Los Angeles, California, USA.
authors.forename: Lauren A
authors.initials: LA
authors.lastname: Simprini
authors.forename: Parag
authors.initials: P
authors.lastname: Goyal
authors.forename: Noel
authors.initials: N
authors.lastname: Codella
authors.forename: David S
authors.initials: DS
authors.lastname: Fieno
authors.forename: Anika
authors.initials: A
authors.lastname: Afroz
authors.forename: Jamie
authors.initials: J
authors.lastname: Mullally
authors.forename: Mitchell
authors.initials: M
authors.lastname: Cooper
authors.forename: Yi
authors.initials: Y
authors.lastname: Wang
authors.forename: John Paul
authors.initials: JP
authors.lastname: Finn
authors.forename: Richard B
authors.initials: RB
authors.lastname: Devereux
authors.forename: Jonathan W
authors.initials: JW
authors.lastname: Weinsaft
mesh_terms: D000368:Aged; D003971:Diastole; D004452:Echocardiography; D005260:Female; D006352:Heart Ventricles / Q000473:pathology*; D006801:Humans; D017379:Hypertrophy, Left Ventricular / Q000473:pathology*; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000473:pathology*; D009206:Myocardium / Q000473:pathology*; D013599:Systole